Drilling head



April 14,1964

Filed Oct. 27, 1961 L. S. AUER DRILLING HEAD INVENTOR.

-BY Hfs rfORMES L. s. AUER DRILLING HEAD April 14, 1964 2 Sheets-Sheet 2 Fil-ed OCt. 2 7, 1961 ,LE-AMD S. as,

INVENTOR.

me M m 4 ff, w

United States Patent() 3,12a614 DRILLING HEAD Leland S. Auer, Sherman Oaks, Calif., assignor to Grant Oil Tool Company, Los Angeles, Calif., a corporation of California Filed Oct. 27, 1961, Ser. No. 148,091 4 Claims. (C1. 64 z3.s)

l This invention relates to well drilling apparatus and more particularly to an improved well drilling head.

In rotary well drilling operations, a rotary table mechanism is employed, which includes a rotatably supported driving element having a non-circular opening therethrough through which a kelly of similar non-circular cross-sectional conguration is slidably extended whereby the kelly can be turned and is capable of vertical movement relative to the table during such rotation. The kelly is attached at its lower end to the upper end of a section of drill pipe which is lowered into the well and rotated during the drilling operation. When the drilling operation has proceeded until the kelly has been lowered as far as possible, the kelly and drill string are raised to connect another section of drill pipe into the string whereupon the kelly is reconnected to the new section and the drilling operation is resumed. In the more commonly used forward circulation drilling operation, the drilling iiuidis pumped downwardly through the interior of the drill string, out the bottom thereof at the bottom of the well bore and upwardly through the annulus surrounding the drill string and between the exterior of the drill string and the interior surface of the well bore. The well Huid moving upwardly through the annulus entrains the cuttings and debris at the bottom of the hole and carries it to the surface of the well. In reverse circulation, the drilling iluid is pumped down the annulus between the drill string and the well casing or well bore, through the drill bit and upward through the drill string. Reverse circulation is advantageous because the well uid has a higher velocity of movement upward through the smaller cross-sectional area at the interior of the drill string and more quickly carries away the cuttings and debris from the bottom of the hole. Reverse circulation type drilling has been hindered in the prior art due to` the absence of a satisfactory means for sealing around the kelly and the drill stem within the drilling head spindle.

Recently, gas or air drilling has become more widely employed. In this drilling operation, compressed gas or air acts as the drilling uid and is injected through the drill stem and drill bit and forced upward through the annulus as the medium for removing the bit cuttings from the well and also to provide a cooling medium for the frictionally heated drill bit.

In drilling operations involving the above-described type of drilling, a drilling head is customarily attached to the top of the Well casing below the derrick door upon which the rotary table to rotate the kelly is mounted. In the prior art, in the most generally used types of drilling heads, such drilling heads usually include an outer casing and a rotatable spindle carried therein. The rotatable spindle is matable with the kelly and rotates with the kelly during the rotary drilling operation. The kelly and drill stem are slidable through the spindle and the kelly rotates with the spindle during the drilling operation. Sealing means are provided in the drilling head between the spindle and the kelly or the sections of drill stem, Whichever is passing through the spindle. The packing is customarily provided about the kelly and drill stem and arranged between these conduits and the rotating spindle. These conventional packings are provided in an attempt to conne the pressures in the well and to prevent the drilling fluid, whether liquid or gas, from escaping between the spindle and the slidable members of the drill string. It can be seen that in reverse circulation drilling operations and gas drilling operations, the eiciencyof the seal is important and in these two types of drilling operations particularly an unusually good seal is required between the drill stem or string and the drilling head, since the fluid in the annulus surrounding the drill string is under greater pressure at the drilling head than that which is encountered in forward circulation operation.

The kelly mustl be progressively lowered vertically through the packing or sealing means contained within the drilling head spindle While drilling is in progress. Additionally, the kelly and drill stem must be periodically moved upward vertically through the sealing means through the drilling head spindle. This is necessary in order to detach the kelly from the drill stem so that an additional section of drill stem may be incorporated in the drill string. Since the kelly is square or hexagonal in configuration, while the drill stem is circular, there is a change of configuration in the members being pulled through the -seal and it is necessary that the seal be so constructed as to act on both the circular cross section and the non-circular cross section. In the prior state of the art, drilling heads are large in size, particularly in height, and are cumbersome and ineicient in operation. Due to such height, elevated structures are required above the well head. It has been difcult with drilling heads of the prior art to obtain good lubrication for the parts which are rotated within the head and such parts are exposed to damage when the spindle assembly is removed to change bits, or perform a like operation.

Accordingly, it is an object of the present invention to provide an improved rotary drilling head which is economical to construct and eicient in operation with a long life and with a minimum of repairs due to isolation of various elements such as oil, dust and sand from those portions of the drilling head to which such elements would be harmful.

It is another object of the present invention to provide.

It is a primary object of the present invention to pro-` vide an improved drilling head assembly for rotary well drilling operations in which the drive unit and wiper for the assembly are removed only when components of increased diameter such as reamers or drill bits are added to the drill string. Y

It is a further object of the present invention to provide an improved drilling head assembly which makes possible the easy addition of drill stem to the drill string without removal of components of the drilling head and their subsequent exposure to harmful elements.

It is yet another object of the present invention to provide an improved drilling head which includes the meansV for lubricating the various elements within the head which are subject to friction, which lubricating means insures a non-contaminated source of lubricant to the various bearings and frictionally engaged surfaces of the drill, ing head. The lubricating device retains oil within the.

3 bit or the like is semiautomatic, but in which the spindle can be locked or unlocked by manual means.

It is a principal object of the present invention to provide a drilling head assembly in which the bearing and packing means of the assembly remain in the head during all drilling operations.

Yet a further object of the present invention is to provide a drilling head assembly which includes shock absorber means for isolating the shock and vibration of the drill string from the components of the drilling head which might be injured by such shock and vibration.

A still further object of the present invention is to provide a drilling head which includes preloaded bearings that compensate for wear to the apparatus during the drilling operation.

The novel features which are believed to be characteristic of the invention both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only and is not intended as a denition of the limits of the invention.

In the drawings:

FIGURE 1 is a view in elevation and partly in section of the presently preferred embodiment of a rotary drilling head in accordance with the present invention;

FIGURE 2 is a sectional plan view taken along line 2-2 of FIGURE 1;

FIGURE 3 is a sectional plan view taken along line 3 3 of FIGURE 1;

FIGURE 4 is a partially schematic view of the drilling head in operation in the condition assumed when drill pipe is added to the string; and

FIGURE 5 is a View corresponding to FIGURE 4 when the spindle assembly is removed to change bits or perform a like operation.

As an illustration of the manner and use of the present invention, a well bore is extended vertically into the earth strata with a well casing disposed in the bore. The drilling iiuid may be either circulated down the annulus between the drill stem and the casing or wall of the well and upwardly through the drill stem, or it may be circulated downwardly through the drill stem and upwardly through the annulus. The purpose of the circulation of the fluid through the well tlow circuit is to take away the cuttings of the drill bit and to provide a cooling medium for the drill bit while drilling is in progress. The present invention is adaptable to both the drilling fluid circuits, one of which is known as reverse circulation while the other is positive or forward circulation. The present invention is particularly adapted to positive circulation using gas or air as the drilling or circulating fluid.

The drilling head of the present invention is indicated generally as 1G and is illustrated in its presently preferred form as attached to the upper end of the well easing by means of a ange 11 thereon. A derrick floor is disposed above the drilling head with a rotary table of conventional construction (not shown) on the upper side of the derrick iloor. The rotary table includes a bushing through which a hexagonally, or non-circular, shaped hollow kelly extends. The table includes means for being rotated by suitable power and power transmitting mechanism whereby the kelly with the drilling string attached thereto may be rotated. The drilling string comprises in general a series of drill stems connected one to the other with the kelly connected to the uppermost drill stem. The drill stem, kelly and the drilling tools attached thereto are referred to as the drilling string. The drilling head of the present invention includes in general a spindle assembly A which is rotatable within the casing and bearing assembly B. A kelly bushing C is atxed to the kelly 4 and is non-circular in both inside and outside configuration, being matable with the configuration of the kelly c-n its interior surface as shown particularly in FIGURES 1 and 3. The kelly bushing is attached to the kelly by bolts 15 such that it is vertically slidable along the kelly, but is non-rotatable with respect thereto. The spindle includes a drive bushing 20 which is generally cylindrical in configuration with an interior wall 21 extending from the upper end thereof, which wall is similar in configuration to the exterior configuration of the kelly bushing C and is thus matable with the kelly bushing. That is, as shown particularly in FIGURE l, the interior surface of the drive bushing extending downwardly from the upper end thereof is indicated as 21 and has a configuration which is generally octagonal such that the kelly bushing is insertable therein and when engaged therewith will be rotated by the kelly and will in turn rotate the drive bushing. The drive bushing proximate its lower end, is decreased in diameter to a diameter which is less than that of the kelly bushing to thereby serve as a stop for the kelly bushing and limit the downward movement therein. Thus, as shown in FIGURE l, at a depth substantially greater than the height of the kelly bushing C, there is an inward protrusion 23 on the drive bushing to a diameter which is'substantially less than the diameter of the kelly bushing C. The drive bushing is made up of three components, namely an interior drive bushing member 24, intermediate shock absorber member 25 and an outer drive bushing member 26. The outer surface 27 of the inner drive bushing member 24 is matable with and bonded to the intermediate shock absorber member 25 which is formed of elastomeric material and which completely separates the inner drive bushing member from the outer drive bushing member 26. Thus, the three members each are generally cylindrical in configuration and taper inwardly proximate their lower end in the orientation of the gures such that the lower end of the outer drive bushing member forms the lower end 29 of the drive bushing. The elastomeric material of the intermediate member has formed therein a circumferentially spaced series of holes 31 which allow increased flexibility of the elastomeric material. Thus, the inner drive bushing member 24 is isolated from the outer drive bushing member 26 by the elastomeric intermediate member 25 to serve as a shock and vibration isolation component. The exterior surface of the outer drive bushing member is of circular cylindrical configuration with an upper end portion having an increased diameter. The upper portion is male threaded downwardly from the upper end thereof and terminates in a horizontal shoulder 37. Thus, the drive bushing comprises in general a cylindrical bushing member with an interior surface that defines an Octagon matable with the kelly bushing and having an inwardly protruding shoulder thereon which acts as a downward limit for movement of the kelly bushing into the drive bushing. The exterior drive bushing member denes an exterior surface which is of circular cylindrical configuration with male threads 38 protruding outwardly proximate the upper end thereof and defining a horizontally extending downwardly facing shoulder 37 which acts as a limit shoulder for engagement with the spindle drive member as discussed more fully hereinafter. The two members are separated and isolated one from the other by the elastomeric isolating member positioned therebetween. Extending downwardly from the lower end 29 of the drive bushing, there is aixed to the drive bushing the wiper member 40 which is formed of elastomeric material and which is adapted to engage the kelly 12 or the drill stem passing through the sealing member in uid sealing engagement. The sealing member is designated generally as 40 and includes a downwardly extending elastomeric member 41 which is generally cylindrical proximate its upper end and tapers inwardly to a diameter less than the minimum diameter of the drill stem or kelly. The wiper member thus has a horizontal upper surface 42 which is approximately equalin annular crosssectional area to the lower surface of the drive bushing such that the wiper member is matable with the bushing. The wiper member is of uniform cylindrical configuration throughout approximately half its height extending downwardly therefrom at which point it tapers inwardly along the surface 43 which serves as the wiping surface for the kelly or drill string. At its innermost sealing diameter, the sealing member is then tapered outwardly to an inner diameter 44 which is somewhat greater than the diameter of the kelly or drill stern to be encountered to allow small enlargements such as drill collars to pass therethrough. Referring particularly to FIGURE 1, it can be seen that the lowermost part of the wiper member is normally urged inwardly into sealing engagement with the drill string, but is flexible outwardly therefrom to allow lateral movement of the drill string. A stiffener finger 46 is bonded into the generally cylindrical upper portion of the wiper member. The stiffener 46 is generally cylindrical with a horizontal flange 47 extending outwardly therefrom such that the stiffener member extends downwardly into the body of the wiper member throughout a portion of its cylindrical segment and then passes outwardly to the outer diameter of the drive bushing. As shown in FIGURE 1, the height of the stiffener at the flange is less than the thickness of the flange 4S of the wiper member such that a layer 49 of the elastomeric material of the wiper member is present between the stiffener flange 47 and the lower surface 29 of the drive bushing to act as a gasket therefor. The lower surface S1 of the stiffener flange, however, from the lower surface of the wiper member flange such that a lock bolt 52 can be utilized to aflix the wiper member to the drive bushing. The lock bolts in the presently preferred embodiment includes a Nyloc pin 53 which serves as a lock means to retain the bolts in place and thus to retain the wiper member in engagement with the drive bushing.

Outwardly from the drive bushing, there is provided a spindle drive member designated generally as 60, which member is generally cylindrical in configuration with a circular cylindrical exterior 61 and interior 62 surface. On the interior surface of the spindle member 60 extending downwardly from the upper end thereof, there is a female threaded indentation 63 matable with the male threads of the drive bushing. The male threads are at a diameter substantially greater than the interior wall 62 of the spindle drive member 60 such that a shoulder 64 is provided at the lower end of the threaded portion,

which shoulder 64 is tapered to serve as a stop surface for the downward movement of the drive bushing into the spindle drive member. That is, the interior surface 62 of the spindle drive member is matable with the exterior surface of the drive bushing. Thus, the drive bushing and wiper member can pass downwardly through the spindle drive member by rotation and engagement of the threads. The downward travel of the drive bushing within the spindle drive member is limited by engagement of the horizontal shoulder of the drive bushing with the upwardly facing shoulder of the spindle drive member. At the exterior surface 61 of the` spindle drive member, there is provided a protrusion 70 at approximately the midpoint of the spindle' drive member. Thus, the spindle drive ring 60 is generally cylindrical in configuration with' an outer vertical wall 61 having a protruding retaining shoulder 70 approximately' at the midpoint of the wall 61. As more fully described hereinafter, the spindle drive ring 60 rotates with the spindle assembly, but remains in place in the drilling head when the drive bushing and wiperV member are removed from the drilling head in order to replace components of relatively large diameter in the drill string.

The housing and bearing assembly designated generally asv B includes an outer housing member having a flange 71 at the lower end thereof which is affixed in sealing engagement with the flange 11 at the upper end of the 6 well casing. Sealing'me'ans such as a sealing gasket' 72 are provided at the mating surface of the flange and the well casing to retain fluid pressure within the well casing. The housing B is again generally cylindrical' in configuration with `an upper portion of enlarged diameter 73 which tapers to a lower portion of decreased diameter 74. A fluid path is provided between the interior wall 76' of the housing at its' lower end and the wiper member which extends therein. A/ fluid outlet 77 is formed in fluid communication with the interior of the drilling head such that fluid can flow as shown upwardly through the well casing through the drilling head housing past the outer surface of the sealing member and outwardly through thev fluid opening 77. A flange 78 is provided for attachment of a suitable fluid conduit to the drilling head housing in order to conduct fluid to or from the well casing and thus from the annulus surrounding the drill string passing through the drilling head. A water nozzle 79 is provided through the lower' portion of the drilling head housing to allow the insertion of water or other fluid when such is necessary orl desirable. The nozzle or inlet 79 can also be utilized" for sampling, injection, instrumentation and the like. Positioned above the fluid outlet is the bearing assembly of the drilling head. The interior wall 76 of the drilling head housing at the upper portion thereof is cylindrical with a vertical wall. The vertical wall 76 is of substantially greater diameter than the outermost diameter of the protrusion 70 on the spindle drive ring. Thus, when the spindle drive ring is contained within the drilling head, the outermost diameter thereof is spaced a substantial distance from the inner wall of the housing assembly. Positioned between the vertical wall 61 of the spindle drive ring and the interior vertical wall of the housing assembly are a plurality of bearing assemblies and fluid sealing assemblies 86a and S6b. The spindle is thus journaled within the housing by a bearing assembly which includes an upper 86a and lower 86b combination radial and thrust bearing assembly. Each of the bearing assemblies includes an inner race 89 and an outer race 90 with tapered roller bearings 91 positionedv therebetween. The inner surface 92 of the bearing racesl is in bearing contact with the outer vertical wall 61 of the spindle drive member while the outer surface of the outer races 90 is in bearing contact with the interior wall 76 of the housing member. Thelower surface of the upper inner race 89 is in bearing contact with the upwardly facing shoulder 66 of the spindle drive ring protrusion 70 while the upper inner surface of the lower bearing race 89 is in contact with the downwardly facing shoulder 67 of the spindle drive ring protrusion. Thus,`

the bearing assemblies are retained in position, and in turn act to limit both the horizontal and vertical movement of the spindle drive ring member which is rotatable retaining ring for positioning the sealing gasket 103 which acts as a fluid seal against the exterior wall y61 of the spindle drive ring 60 during rotation thereof. An annular recess 104 is provided in the exterior wall of the`y retainer ring with an O-ring seal 105 positioned therein.

A series of circumferentially spaced recesses 106 extending downwardly from the upper surface of the'retaining ring are provided to position a plurality of rsprings 106v Considered as a whole, however, the lower retaining ring has an inner diameter approximately equal to but greater thanV the outer diameter of the spindle drive member and an outer diameter Iapproximately equal to the inner diameter' of the interior wall 76 of the housing at its cylindrical" portion. An annular indentation 102 is provided in the" which urge the outer race of the bearing assembly upwardly against the tapered bearings such that a preload is continuously provided on the bearings to compensate for wear thereof. The bearing race is thus preloaded such that the races are constantly urged into bearing engagement with the roller bearings when wear occurs during operation.

Positioned within the recesses of the retainer rings are sealing gaskets 103 which are similar in configuration. Referring particularly to FIGURE 1, each of the sealing gaskets includes an upper and lower sealing member 103a and 10317 which is formed as shown in the figure with a normally outwardly urged lip which is urged into engagement with the wall of the spindle drive member. As shown in the ligure, the two portions of the sealing gasket `are inverted relative one to the other such that a recess 107a or 107b is defined in each member where fluid in the recess increases the outward force on the lip. Thus, if fluid is able to ow into the recess 107a or 107b it pushes the lip outward more rmly into sealing engagement with the wall of the spindle drive member. A generally T-shaped annular back-up ring 109 is positioned between the two members and extends to an inside diameter approximately equal to but greater than the outside diameter of the vertical wall of the spindle drive member. The generally T-shaped back-up ring 109 has a slope at the inner surface of the T which is generally mateable with the angle of the surface of the sealing members 103a and 103b to keep the lips of the sealing rings from collapsing. Thus, it may be seen that in both the upper and lower sealing ring assemblies the lips are urged into sealing engagement with the wall and the engagement is increased when pressure is formed in the cavity 107a proximate the upper lip and in the cavity 107b proximate the lower lip. The lips therefore prevent the passage of iiuid in either direction along the wall of the retainer member or along the wall of the spindle drive member.

As can thus be seen in FIGURES 1 and 3, a cavity 110 which is annular in configuration is formed between the bearing races and the housing, which cavity is kept iilled with oil as described hereinafter, with the oil maintained under a pressure somewhat greater than atmospheric. The oil serves to lubricate the bearings and is retained within the bearing assembly section by the double sealing rings described hereinbefore. Thus, oil under pressure which seeks to pass outwardly from the cavity along the wall of the spindle drive member enters the recess of the sealing ring and forces the lip into sealing engagement with the spindle drive member. uid passes upward along the wall 61 to the lower lip 103b it fills the recess 107b and forces the lip into further engagement with the wall 61. The oil within the cavity which serves to lubrieate the bearings is retained therein by the double sealing rings while foreign material and drilling tiuid is kept from entering the oil reservoir by the outer lips of the sealing rings. An oil reservoir 114 is formed upon the outer Wall of the drilling head housing with an opening 115 through the wall of the housing into the annular cavity 110 between the bearing assemblies. The oil reservoir is provided with an oil inlet cock 116 and an oil outlet cock 117. Additionally, an air tting 118 is provided through the wall of the oil reservoir in order that an air line can be connected to the reservoir to maintain a pressure somewhat above atmospheric within the oil reservoir. In the presently preferred embodiment a pressure is maintained which is approximately 2 p.s.i. greater than the annular pressure in the well to insure that oil is circulated to the bearings under positive pressure and that the pressure upon the sealing rings is greater in the oil reservoir than on the exterior of the oil reservoir to assure the prevention of entry of any material from the annulus to the reservoir through the port 115. In addition to the double acting sealing rings, additional seals are provided by means of a sealing gasket 120 which is annu- Conversely, when well lar in configuration and spans the lower retaining ring and the outer wall of the spindle drive member. A similar sealing gasket 121 is provided at the upper surface of the upper retaining ring and spans the opening between the drive member. A drive bushing seal 119 is provided in an annular recess in the inner wall of the spindle drive member and drive bushing to furnish a fluid seal therebetween.

An annular top plate 122 is atiixed to the wall of the housing and extends inwardly to an inside diameter approximately equal to but greater than the maximum diameter of the threads of the drive bushing. The top plate is retained in position by a plurality of circumferentially spaced bolts 123 with a Nyloc retainer pin to lock the bolts in position. Thus, the spindle drive member cannot be removed from the housing, nor can the retainer rings or bearing assemblies, without removal of the top plate 122 of the drilling head. The drive bushing and the wiper member aflixed thereto can, however, be removed through the central opening of the top plate. An opening 124 is provided through the top plate coextensive with a hole 125 in the top surface of the spindle drive member such that a pin 126 can be inserted through the top plate and into the spindle drive member to prevent rotation thereof. Thus, when it is desired to remove the inner portions; that is the drive bushing and sealing member, from the drilling head assembly, it is necessary only to insert the pin into position thereby locking the spindle drive member and housing together, after which rotation of the kelly will rotate the drive bushing from the spindle drive member and allow it to be removed from the drilling head.

Thus, referring to FIGURES 4 and 5, in operation when the drill stem is being added to the drill string the complete operation takes place without removal of any of the components from the drilling head. That is, as shown in FIGURE 4, the kelly with the kelly bushing C attached thereto is raised from the drilling head such that the kelly bushing is removed from the recess in the drilling head with which it is mated during the drilling rotation. The kelly can then be moved vertically upward through the drilling head until the drill stem is exposed and another length of drill stern is inserted in the string. When, however, it is necessary to insert a component in the drill string such as a bit or reamer which cannot pass through the normal openings in the drilling head, the drive bushing 20 and wiper 40 assembly are removed by locking the spindle drive member into engagement with the housing, after which the kelly bushing is rotated while in the engaged position with the drilling head, causing the threads between the drive bushing and spindle drive member to become disengaged so that the drive member and wiper member can be removed vertically from the drilling head as shown in FIGURE 5. It is to be noted that when these components are removed, none of the bearings or critical components of the drilling head are exposed.

What is claimed is:

1. A well drilling head for confining fluid within a well by surrounding and sealing against a rotatable drill string including a kelly of non-circular cross-sectional configura tion: a kelly bushing adapted to engage the kelly in longitudinally sliding engagement for rotation therewith; a spindle assembly non-rotatably mated with said kelly bushing for rotation thereby, said spindle assembly including a drive bushing member, a wiper affixed to said drive bushing member and depended therefrom and adapted for sealing contact with the drill string, and a spindle drive member; a bearing assembly, said bearing assembly rotatably mounting said spindle drive member for rotation of said spindle assembly about the axis of the drill string; a housing enclosing said bearing assembly, said housing having an axial opening therethrough for the passage of said drill string and for engagement of said kelly into said kelly bushing, sealing means within said housing enclosing a cavity surrounding said bearings, means supplying lubricant to said cavity, and means for mounting said drive bushing and Wiper assembly within said spindle drive member for selective removal therefrom with said kelly bushing, said spindle drive member having an inside diameter greater than said drill string.

2. A well dril-ling head for conflining iluid within a well by surrounding and sealing against a rotatable drill string including a kelly of non-circular cross-sectional configuration: a kelly bushing adapted to engage the 'kelly in longitudinally sliding enga-gement for rotation therewith; a spindle -assembly non-rotatably mated wi-th said kelly bushing for rotation thereby, said spindle assembly including a drive bushing member, a wiper aixed to said drive bushing member and `depended therefrom and adapted for sealing contact with the drill string, and a spindle drive member; a bearing assembly, said bearing assembly rotatably mounting said spindle drive member for rotation of said spindle assembly about the axis of the drill string; a housing enclosing said bearing assembly, said housing having an axial opening therethrough for the passage of said drill string and for engagement of said kelly into said kelly bushing; said housing defining an annular closed cavity, said bearing assembly positioned within said annular cavity; means for supplying lubricant to said cavity at a pressure above the pressure within said housing exteriorly of said cavity, and means for mounting said drive bushing and Wiper assembly within said spindle drive member for selective removal therefrom with said kelly bushing, said spindle drive member having an inside Idiameter greater than said drill string.

3. A Well drilling head for conning fluid within a well by surrounding and sealing against a rotatable drill string including a kelly of non-circular cross-sectional configuration: a kelly bushing adapted to engage the kelly in longitudinally sliding engagement fo rrotation therewith; a spindle assembly non-rotatably mated Awith said kelly bushing lfor rotation thereby, said spindle assembly including a drive bushing member, a rwiper aflixed to said drive bushing member and depended therefrom and adapted for sealing contact with the drill string, and a spindle drive member; said spindle drive member having a generally cylindrical exterior sur-face, a circumferential protrusion extending radially from said exterior surface to said spindle Idrive member; a bearing assembly, said bearing assembly rotatably mounting said spindle drive member for rotation of said spindle assembly about the axis of the drill string, said bearing assembly being in radial bearing contact with said exterior cylindrical 'wall of said spindle and in longitudinal bearing contact with said circumferential protrusion; a housing assembly enclosing said bearing assembly, said housing having an axial opening therethrough for the passage of said drill string and for engagement of said kelly into said kelly bushing; sealing means within said housing enclosing a cavity surrounding said bearing, means supplying lubricant to said cavity, and means for mounting said drive bushing and wiper assembly within said spindle drive member for selective removal therefrom with said kelly bushing, Said spindle drive member having an inside diameter greater than said drill string.

4. A well drilling head for confining tluid within a well by surrounding and sealing against a rotatable drill string including a kelly of non-circular cross-sectional configuration: a kelly bushing adapted to engage the kelly in longitudinally sliding engagement for 4rotation therewith; a spindle assembly non-rotatably mated with said kelly bushing for rotation thereby, said spindle assembly including a `drive 'bushing member, a wiper aflixed to said drive bushing member and depended therefrom and adapted for sealing contact with the drill string, and a spindle drive member; said spindle drive member having a generally cylindrical exterior surface, a circumferential protrfusion extending lradially [from said exterior surface -of said spindle drive member; a Ibearing assembly, said bearing assembly rotatably mounting said spindle drive member for rotation of said spindle assembly about the axis of the drill string, said bearing assembly being in radial bearing contact 'with said exterior cylindrical wall of said spindle and in longitudinal bearing contact with said circumferential protrusion; a housing assembly enclosing said bearing assembly, said housing having an axial opening therethrough for the passage of said drill string and for engagement of said kelly into said kelly bushing; said housing defining an annular closed cavity, said bearing assembly positioned within said annular cavity; means for supplying lubricant to said cavity at a pressure above the pressure within said housing exteriorly of said cavity, and means for mounting said drive bushing and wiper assembly within said spindle drive member for selective removal therefrom with said kelly bushing, said spindle drive member having an inside diameter greater than said drill string.

References Cited in the file of this patent UNITED STATES PATENTS 2,170,916 Schweitzer et al. Aug. 29, 1939 2,795,398 Ragland June 1l, 1957 2,846,247 Davis Aug. 5, 1958 2,865,218 Bishop Dec. 23, 1958 2,995,196 Gibson et al. Aug. 8, 1961 3,052,300 Hampton Sept. 4, 1962 

1. A WELL DRILLING HEAD FOR CONFINING FLUID WITHIN A WELL BY SURROUNDING AND SEALING AGAINST A ROTATABLE DRILL STRING INCLUDING A KELLY OF NON-CIRCULAR CROSS-SECTIONAL CONFIGURATION: A KELLY BUSHING ADAPTED TO ENGAGE THE KELLY IN LONGITUDINALLY SLIDING ENGAGEMENT FOR ROTATION THEREWITH; A SPINDLE ASSEMBLY NON-ROTATABLY MATED WITH SAID KELLY BUSHING FOR ROTATION THEREBY, SAID SPINDLE ASSEMBLY INCLUDING A DRIVE BUSHING MEMBER, A WIPER AFFIXED TO SAID DRIVE BUSHING MEMBER AND DEPENDED THEREFROM AND ADAPTED FOR SEALING CONTACT WITH THE DRILL STRING, AND A SPINDLE DRIVE MEMBER; A BEARING ASSEMBLY, SAID BEARING ASSEMBLY ROTATABLY MOUNTING SAID SPINDLE DRIVE MEMBER FOR ROTATION OF SAID SPINDLE ASSEMBLY ABOUT THE AXIS OF THE DRILL STRING; A HOUSING ENCLOSING SAID BEARING ASSEMBLY, SAID HOUSING HAVING AN AXIAL OPENING THERETHROUGH FOR THE PASSAGE OF SAID DRILL STRING AND FOR ENGAGEMENT OF SAID KELLY INTO SAID KELLY BUSHING, SEALING MEANS WITHIN SAID HOUSING ENCLOSING A CAVITY SURROUNDING SAID BEARINGS, MEANS SUPPLYING LUBRICANT TO SAID CAVITY, AND MEANS FOR MOUNTING SAID DRIVE BUSHING AND WIPER ASSEMBLY WITHIN SAID SPINDLE DRIVE MEMBER FOR SELECTIVE REMOVAL THEREFROM WITH SAID 